I recently got it into my head to compare the various popular video codecs in an effort to better understand how av1 works and looks compared to x264 and x265. I also had ideas of using a intel video card to compress a home video security setup, and what levels of compression I would need to get good results.
The Setup
I used the 4k 6.3gb blender project, tears of steel as a source. I downscaled the video to 1080p using all three codecs, and then attempted to compare the results using various crf levels.
To compare results I used imgsli, FFMetrics, and my own picture viewer to try and see what the differences are.
The Results
| crf | av1 KB | x265 KB | x264 KB |
|---|---|---|---|
| 18 | 419,261 | 632,079 | 685,217 – x246 visually lossless |
| 21 | 352,337 | 390,358 – x265 visually lossless | 411,439 |
| 24 | 301,517 – av1 VAMF visually lossless | 250,426 | 263,524 – x264 good enough |
| 27 | 245,685 | 165,079 – x265 good enough | 176,919 |
| 30 | 205,008 | 110,062 | 122,458 |
| 33 | 168,192 | 73,528 | 86,899 |
| 36 | 139,379 – av1 My visually lossless | 48,516 | 63,214 |
| 39 | 116,096 | 31,670 | 47,161 |
| 42 | 97,365 – av1 my good enough | 20,636 | 35,801 |
| 45 | 81,805 | 13,598 | 27,484 |
| 48 | 69,044 | 9,726 | 20,823 |
| 51 | 58,316 | 8,586 – worst possible | 16,120 – worst possible |
| 54 | 48,681 | - | - |
| 57 | 39,113 | - | - |
| 60 | 29,062 | - | - |
| 63 | 16,533 – worst possible | - | - |
I go into more detail with the hows and whys of my choices, in my journal-style blog post, as well as how i came to these conclusions, But in essence, if you want to lose practically no visual information, crf24 through 36 for av1, crf 21 for x265, and crf 18 for x264 will do the job.
If you are low on space, using my 'good enough' choices will get you practically the same visual results while using less space, depending on the codec.
I did try to format the table here better. I used code blocks the first time, and it ended up being even uglier. After about four edit attempts i kinda just gave up. Tables don't seem to exist as far as I can tell either.
Your experience with x264 just about matches up with mine. As long as I don't pixel peep, crf 24 does a pretty great job of conveying the information. It also does a pretty great job of working with just about everything compatibility-wise. I don't expect it to go away any time soon specifically because of that.
AV1 is super neat in that we can buy hardware accelerated encoding for it for really cheap using the Intel Arc video cards, and can be decoded by their latest CPU generation. It makes for a great choice for something like security camera footage where playback compatibility is good enough (you can play it in a modern pc), hardware encoding works with a 200$ card, and you save a lot of money using the video card instead of buying extra storage space.
With $200, you could buy ~12TB worth of HDD(s) instead. You'd need >36TB of video for that to make financial sense and you'd always lose quality.
Additionally, you'd have to factor in the power it needs to transcode but, with HW accel, it's not quite as much as with CPUs.
Sure, but that is a choice that couldn't be made without first checking how much space is saved by switching codecs. This helps with making that decision, but i'm well aware it is only part of the information needed.
Oh the data is absolutely fine and helpful; I only take issue with the conclusion ;)